*{
    margin:0;
    padding:0;
}
.wrapper{
    width: 500px;
    height: 500px;
    margin:100px auto;
    position: relative;
    border:1px solid black;
}
.start{
    height: 40px;
    width:80px;
    border:1px solid black;
    margin:10px auto;
    text-align: center;
}
.right{
    width: 300px;
    height: 300px;
    position: absolute;
    margin:auto;
    top: 0;
    bottom: 0;
    right: 0;
    left: 0;
    
}
.imgA{
    width: 300px;
    height: 300px;
    position: relative;
    
}
.imgA .imgC{
    position: absolute;
    border-radius:4px;
   
    background: url(./img/1.jpg);
    box-shadow: 0 0 8px #fff;
    z-index:2;
    
}
.imgB{
    position: absolute;
    border-radius:4px;
   
    background: url(./img/3.jpg);
    box-shadow: 0 0 8px #fff;
    width: 300px;
    height: 300px;
    z-index: 1;
}
